Pulse landing system



Dec.`30, 1947. N. MARCHAND v 2,433,381

PULSE LANDING SYSTEM n Filed sept. e, 194s 2 sheets-'sheet 1 CONT/POL Raf/VERI] ATTORNEY PULSE LANDING SYSTEM Filed sept. 6, 1943 N. MARCHAND 2,433,381

2 Sheets-Sheet 2V lAlfm INVENTOR. NATHAN MARCHAND ATTPNEY Patented Dec. 30a H1947 2,433,381 PULSE LANDING SYSTEM Nathan Marchand, New York, N. Y.. Aassigner to Federal Telephone and `Radio Corporation, .East Newark, N. J., a corporation of Delaware Application september c, 1943, serial No. 501,"3'42 (ci. 25o-1.52)

20 Claims.

This invention relates to radio beacons and more particularly to a method and means for de- 'fining a radio beacon course by the use Vof -short pulses of energy.

Many aircraft are now equipped with standard distance determining equipment. This equipment generally transmits a short pulse of energy at periodic intervals which, after reflection, is received on the craft, An indication of the time of traversal of the pulse to vand from the reilectingobject is produced to show 'the distance of the craft -from this reflecting object. Furthermore, in the tart fof aircraft "navigation, beacons 'are commonly iised t() indicate a course line to show the alignment of the 4'runway and to denne 'a glide path for :guiding a.ircrfaft into the landing Aon the runway. y Y -It is an object of imy invention to provide a lcircuit utilizing the present Idistance determining equipment on an 'airc'raftin combination with y'a pulse controlled beacon transmitter to provide the desired 'beacon transmissions and corresponding course and distance indications -on the craft.

It 'is a further object of my invention to provide a method fand means for producing a beacon indication wherein a -Shofrt 'pulse is transmitted irom a craft to a receiving station and V-in Vresponse to this received pulse overlapping beacon patterns are transmitted lto dene the desired course. Y

It is a still further object of my invention to .provide va beacon transmitter arrangement which -is 'triggered by `a received pulse to transmit short beacon pulses defining a 'desired beacon path.

Further objects Tand features of my invention f" may be had from the specific `'description thereof made with reference to the accompanying drawing, in which:

Fig. 1 is a diagrammatic illustration ofthe apparatus and the beacon patterns produced in accordance with my invention;

Fig. 2 is a circuit 'diagram of a `speciiic `embodiment of -iny invention; and

Fig. 3 is an illustration of possible patterns produced on the indicator illustrated in Fig. f2.

Turning `rst torFig. -1, a distance and course indicating `system l0 is shown mounted fin van aircraft I4. This distance and course indicating system serves to transmitshort pulses to controlreceiver Il. Control-receiver ll then 4serves fto trigger localizer beacon l 2 to produce .alternately the overlapping el'd patterns 'l5 and l'. These patterns are preferably produced only momentarily by a short transmitted Lpulse so that the .pulses may be received on and .properly Noperate so the distance and course indicating system l0. By comparison of the pulses from patterns l5 `and i5, the pilot may be apprised of -his position relative to the localizer course. 1n addition to localizer beacon l2, received energy also serves to trig- 'ger a glide path bea-con l3 which serves to produce a glide path line II in the vvertical plane f|8 intersecting the localiser course line. Indication 4or this glide path is also produced on the craft '|'4 by the distance kc'culrse indicating system l0.

Turning now to Fig. .2, a circuit arrangement 'more `clearly Vdenning the apparatus illustrated in Fig. Yl. is set forth. 'The 'distance and course in"- dicat'ing system Hl may comprise an impulse 'source 2li which is coupled 'to transmitter-2] serving to transmit 'short pulses of energy. Irnpulse source 210 also serves to time the operation 'of a vsweep circuit Y22 which applies a sweep volti 'age 4across plates 26 of cathode ray indicator l"125.

At the 'same time, the impulses from source 20 may Voperate receiver blocker 'Q3-which serves to block the receiver `P24 during intervals while'transmitter 2l is in operation. "The -output of receiver `24 is applied across vertical deflected plates 2? of cathode ray indicator `25 so that received energy will appear as 'vertical deections -of the cathode ray beam as it traverses between plates '216.

The transmitted pulses from transmitter 2 'I are Ereceived at 4lfl and 'applied to receiver 30 which Yserves to rectify lthe pulse-to produce a direct current impulse therefrom. This impulse is then de'- layed successively 'over delay-lines' 40 and 4l 'producing therein delays A, B, respectively. The deilayed A'received pulse, fafter passing network 40,1i's applied -t`o a-relay "42 `'and 'after passing delay network 4| is applied to a relay `43. .All this `equipment may -be Vconsidered fas arranged -at local-izer lbeacon 12. A radio frequency source 44 adapted lto be connected over =a switch arrangement to the fantenna elements 45, 216 and '41 is 'provided forming with the antennas and switches aknown type Yof radio beacon. Normal-ly, the switch is in ya neutral 'position `so thatno-energyfrom source 44 is applied to 'the `arite'nna elements. On applica*- tion 'of the delayed pulse toirelay 42, however, the switch 'is operated to energize these antennas transmitting Ta short rr'pi-ilse PA over pattern T6. This pulse passes quickly and relay '42 is de'energized, returning 'the switch to JVnormal. A short interval thereafter, l'depe'nd'ez'it uupon the delay -B, relay 43 lis operated, energizing 'the antennas '45,

pulse PB servingr Ito vproduce indicator pattern '1?5. YEnergy "-deningpatte'rns t5 Land IKS is successively received on receiver 24 of the craft and applied across the vertical deflector plates 21 producing two indicating pulses IA, IB, as shown. If the craft is on course, the indicating pulses IA, IB are of equal amplitude, as shown in the left hand screen of Fig. 3. If the craft is not on course, however, the impulses IA and IB are of unequal amplitude as shown in the pattern at the right of Fig. 3 and the direction of departure of the course may be determined by the sense of departure from equality of the received pulses. This arrangement by itself may serve at a radio course beacon or may serve as a localizer beacon at an airport.

If the beacon l2 is a localizer beacon, it may be desirable to also provide at the airport a glide path beacon to guide the craft to a landing. The glide path beacon may be energized from the same source 44, as shown in Fig. 2. In this arrangement, glide path beacon I3 includes additional delay lines 59 and 5| producing further delays C and D in the pulse received at 3S. This pulse, after delay C is applied to relay 52 and after delay D to a relay 53, and serves alternately to connect source 44 to vertically arranged antennas 54 and 55, respectively. These antennas 54 and 55 may constitute an equi-signal glide path system, the antennas being arranged at different vertical heights such that a radiation lobe from antenna 55 will overlap a null in the radiation pattern of antenna 54. A more complete description of the operation of this type of glide path beacon may be had by reference to copending application of Chester B. Watts, Jr., Serial No. 444,988, filed May 29, 1942, now Patent 2,406,876 granted Sept. 3, 1946. It is clear, however, that any desired type of glide path beacon may be used in place of the specific type shown. Energization of antennas 54 and 55 produces additional transmitted pulses PC and PD which are also received on receiver 24 and applied to vertical deector plates 21. These pulses produce additional indicator pulses on the screen of cathode ray oscillograph 25, as shown at IC and ID.

Because of additional delay caused by lines 50 and 5l, these pulses will be spaced apart a predetermined distance and will also be spaced from indications IA and IB.

In Fig. 3 the pulse indications IC and ID are shown, in the left hand portion thereof, equal in amplitude indicating that the craft is on the glide path course and in the right hand portion are shown to be of unequal amplitude indicating the craft is off the glide path course. It is clear that this inequality likewise shows the direction of departure of the craft above and below the desired glide path line so that the pilot can make the necessary correction.

In addition to indicating the position of the craft relative to the course, it is clear that the received impulse indications will also be spaced along the screen in accordance with the distance of the transmitting beacon from the craft. For this purpose, it is desirable to use the first received impulse IA for distance determination. This distance indication may readily be made by giving to delay network A a fixed delay representing a fixed distance, for example, a two mile distance on the screen. Thus, by subtracting this correction factor from the distance indication made on the indicator, the distance of the craft from the beacon may be readily determined. Furthermore, the transmitted pulses are preferably of considerably greater amplitude than normal reflected pulses so that there is no confusion between the course indicating pulses on the screen and the normal distance indicating pulses received from reflecting objects. Furthermore, the beacon pulses, if reflected from objects in the vicinity of the course will be received at a later time at receiver 24 than the directly transmitted beacon pulses so that the probability of following a false course because of reflections will be substantially eliminated. v

In addition, if transmitter 2! and receiver 24 operate on the same frequency, the normal distance determining feature of the apparatus may be used to indicate the altitude of an aircraft above the earth. Thus, the pulse reflected from the earth will be received on receiver 24 and will produce a definite indication as shown at IG, Fig. 3, indicating thealtitude of the craft above the earth. Thus, thedevice may provide an absolute altimeter as well as a beacon indicator without any necessary additional equipment. Under these circumstances, precautions must be taken to prevent receiver 30 from being triggered by transmitted impulses IA, IB, etc. To this end a blocking circuit 48 is provided to block receiver 30 for a suflicient length of time for the pulse to pass all the delay lines 40, 4I, 5B and 5l. This circuit may be of any desired type, for example, a trigger circuit which is turned into a blocking condition by the pulse applied from the outlet of 4i), and which will return to its original position at a fixed time later.

It is clear also that, if desired, source 44 may be of a different radio frequency than that transmitted from transmitter 2| and receiver 24 may be tuned to this frequency in which case the receiver blocking circuit 23 may be eliminated. However, in this case, the altimeter feature of the system will not be present since the pulses reflected from the earth will not be of the proper frequency to be received at 24. It is clear also that other forms of equi-signal beacons may be used in place of the specific type illustrated at 45, 46 and 41, for example, the well known cross coil type may be provided, if desired. Likewise, any type of glide path beacon may be provided although the equi-signal type is preferred rather than constant intensity type Delay lines 40, 4|, 50 and 5l may be arranged in parallel instead of series, the respective delays then being made progressively greater to afford the desired separation of indications on the screen.

The beacon arrangement in accordance with my invention requires relatively low power equipment since pulses are transmitted only for brief intervals of time. Furthermore, if desired, the beacon transmitter may be turned on only in response 'to energy received so that the radio frequency is operative only at the time the beacon is desired for guiding a craft.

This type of system is particularly useful for guiding a craft along a narrow,fcrooked course since then the beacons may be made of relatively low power so as to be ineffective a short distance from the beacon itself. A plurality vof such beacons vmay Vthen be arranged along a course spaced apart a suiiicient distance to avoid overlapping of the beacon courses, as defined, and then may be successively triggered into operation by the equipment on the craft Vas each beacon is approached.

While I have described above the principles of my invention in connection with specific apparatus, and particular modifications thereof, it is to be clearlyeunderstoo'd'.that this descriptionv is madeV only by way'. of example; andA notas a lirnitationonthe scope ofmy invention Set forth in the objects of my invention and the accompanvine claims.

What is claimed is: Y

` 1. A system for guiding craft along a pre-determined course comprising means on said craft for transmitting a pre-determined signal, transmitter means for transmitting energy in two patterns in overlapping relation on opposite sides of said course, receiver means for receiving said signal, means responsive to said receiver signal for operating said transmitter means to transmit successively a course signal over respective of said two patterns, receiver means on said craft for reoeiving said transmitted course signal, and means for. comparing the received course signal to indicate the position of said craft relative to said course.

2. A system for guiding craft along a predetermined' course, comprising means on said craft for transmitting a predetermined short pulse, transmitter means for transmitting energy in two patterns in overlapping relation on opposite sides of said course, receiver means for receiving said pulse, means responsive to said received pulse for operating said transmitter means to transmit successively an energy pulse over` respective of said two patterns, craft receiver means on said craft for receiving said transmitted energy pulses, and means for comparing the amplitudes of said receivedenergy pulses to indicate the position of said craft relative to said course.

3. A system according to claim 2, further comprising means for indicating the distance of said craft from said transmitter means in response to the irst of said received pulses.

4; A system according to claim 1, wherein said craft is an aircraft, and wherein said craft receiver means is operative to` receive said predetermined signal after reflection from the earth, and means for indicating the distance of the craft from the earth in response to said received reflected pulse. n A

5. A method of guiding a craft along a predetermined course,l comprising transmitting from saidcraft a predetermined signal, receivingv said signal at a position spaced along said course at a predetermined location, successively transmitting in response to said received signal, course signals over separate field patterns overlapping along said course line, receiving on said craft said course signals, and comparing the said received course signals to determine the position of said craft relative to said course line.

6. A method according to claim 5, further comprising producing an indication of the distance of said craft from said position in response to the first received of said course signals.

'7. A method according to claim 5, further comprising receiving said signal, after reflection from the earth, on said craft and determining the distance of said craft from the earth in response to said received reflected signal.

8. A system for guiding a craft along a pre-determined course comprising transmitter means on said craft for transmitting a pre-determined signal, means for receiving said signal, directive transmitter means arranged along said course line, means controlled by said received signal for providing signals of different characteristics, means for applying signals of one of said characteristics to said directive transmitter, means to produce a first beacon signal transmitted over a pre-determined directive eld pattern, means for applying signals of another of said characteristics to said directive transmitter means to produce a second` beacon signal transmitted over a pre-determined second `field pattern overlapping said first eld pattern to define said 0011156, 1'6- ceiver means on said craft for receiving said rst and second beacon signals, and means for oomparing said first and second received signals to indicate the location of said craft with respect to said course.

9, A system for guiding an aircraft along a predetermined course comprising transmitter means on said craft for transmitting a predetermined signal,y means on the ground for receiving said signal, directive transmitter means arranged along said course line, first and second delay means in the output of said receiver means for delaying said received signal for a rst and a second time interval, means for applying said received signal after passing said first delay means to said directive transmitter means to produce a first beacon signaltransmitted over a predeterq mined directive ileld pattern, means for applying said. received signal, after passing said second delay means to said directive transmitter to produce a second beacon signal transmitted over a predetermined second directive field pattern overlapping said first field pattern to define said course, receiver means on said craft for receiving said rst and second transmitted beacon signals, and means for comparing the said rst and second received signals to indicate the location of said craft with respect to said course,

10. A system according to claim 9, wherein said directive transmitter means operates to transmit energy at the same radio frequency as said transe mitter means on said craft.

11. A system according to claim 9 wherein said means for applying said receivedV signal after passing said first and second delay means, comprises respective rst and second relay means for the differently delayed pulses, and keying means responsive t0 operation of said relays for providing said first and second directive patterns.

12. A system according to claim 9, in which said transmitter means arranged along said course line is a localizer beacon transmitter, 'furv ther comprising glide path transmitter means arranged in the vicinity of said localizer beacon and adjusted to dene a glide path line along said course line, further delay means for imparting a still different delay to said received signal, and means for applying said still further delayed signal to said glide path transmitter'means to define said glide path line.

13. In a system for guiding craft along a predetermined course wherein a signal transmitter, a signal receiver and means for comparing received signals are provided on said craft, transmitter means for transmitting energy in two patterns in overlapping relation on opposite sides of said course, receiver means for receiving signals from said signal transmitter, means responsive to said received signals for operating said transmitter means and means to transmit successively course signals over respective of said two patterns.

14. In a system for guiding craft along a predetermined course wherein a signal transmitter, a signal receiver and means for comparing received signals are provided on said craft, means for receiving signals from said signal transmitter, means controlled by said received signals for providing signals of different characteristics, directive transmitter means, means for applying signals of one of said characteristics to said transmitter means to produce a first beacon signal transmitted over a pre-determined directive eld pattern, and means for applying signals of another of said characteristics to said transmitter means to produce a second beacon signal transmitted over a pre-determined second directive eld pattern overlapping said first eld pattern to define said course.

15. In a system for guiding craft along a predetermined course wherein a signal transmitter, a signal receiver and means for comparing received signals are provided on said craft, means for receiving signals from said signal transmitter, directive transmitter means arranged along said course line, first and second means in the output of said receiver means for delaying said received signal for a -rst and a second time interval, means for applying said received signal after passing said rst delay means to said directive transmitter means to produce a rst beacon signal transmitted over a pre-determined directive eld pattern, and means for applying said received signal after passing said second delay, means to said directive transmitter to produce a second beacon signal transmitted over a predetermined signal eld pattern overlapping said first field pattern to define said course.

16. A radio beacon responsive to received signals for producing a beacon guiding course comprising means for receiving said signals, directive transmitter means arranged along said course line, rst and second delay means in the output of said receiver means for delaying said received signal for a first and a second time interval, means for applying said received signal after passing said rst delay means t said directive transmitter means to produce a rst beacon signal transmitted over a predetermined directive iield pattern, and means for applying said received signal, after said second delay means to said directive transmitter to produce a second beacon pulse transmitted over a predetermined second directive field pattern overlapping said rst field pattern to define said course.

A17. A radio beacon according to claim 16, wherein said means for applying said received signal after passing said first and second delay means, comprises respective first and second relay means for the differently delayed signals, and keying lneans responsive to operation of said re- 8 lays for providing said rst and second directive patterns.

18. A radio beacon according to claim 16, in which said transmitter means is a localizer beacon transmitter, further comprising glide path transmitter means arranged in the vicinity of said localizer beacon and adjusted to define a glide path line along said course line, further delay means for imparting a still diierent delay to said received signals, and means for applying said still further delayed signals to said glide path transmitter means to define said glide path line.

19. A method of guiding an aircraft along a predetermined course, comprising transmitting from said aircraft a predetermined signal, receiving the ground signal thereof, delaying said received signal for a iirst and a second time interval, producing and transmitting in response to said received signal, after delay of said first time interval, a rst beacon signal over a predetermined directive field pattern, producing and transmitting in response to said received signal, after said second delay, a second beacon signal over a predetermined second directive eld pattern overlapping said irst eld pattern to define said course, receiving on said craft said iirst and second transmitted beacon signals, and comparing the said first and second received signals to indicate the location of said craft with respect to said course.

20. A method according to claim 19, in which said rst and second patterns serve as a localizer beacon transmitter for dening a localizer course line, further comprising, imparting a still different delay to said received signal, and producing in response to said still further delayed signal a glide path line in the vertical plane passing through said localizer course line.

NATHAN MARCHAND.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,134,716 Gunn Nov. 1, 1938 2,132,599 Baumann Oct. 11, 1938 2,321,698 Nolde June 15, 1943 

